JPS61225592A - Method to improve fluidizing property of two-phase flow utilizing electric field - Google Patents

Abstract

PURPOSE:To obtain a large amount of fluid flow by small electric power, by flowing fluid in the neighborhood of the center of a pipe, by gathering gas in the neighborhood of the inside wall of a pipe, by applying high voltage across a wire electrode and a mesh electrode. CONSTITUTION:A wire electrode 12 is provided on the inside wall of a pipe 1 along the axial direction of a pipe 1, and a mesh electrode 13 is provided surrounding the outer side of a wire electrode 12. The wire electrode 12 is in no contact with the mesh electrode 13. When high voltage is applied across the wire electrode 12 and the mesh electrode 13, a gas 3 is driven out in the direction of a mesh electrode 13, of which electric field is weaker. The gas 3 gathers in the neighborhood of the inside wall 4 of a pipe 1, while a fluid 2 flows through the part in the neighborhood of the center of a pipe 1. With such an arrangement, the heat transferring rate can be increased in both regions of a foamed gas flow and of a ring fluid flow in a boiling heat exchanger. Since a fluid runs through the region in the neighborhood of the center of a pipe out of two-phases flow in the pipe, pressure loss is lowered, and a large amount of flow can be circulated by small electric power.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of improving the flow characteristics of two-phase flow in a conduit using an electric field.

(Prior art) Conventionally, in a heat exchanger that transfers heat to a liquid such as water or fluorocarbon flowing in a pipe to boil it, in the direction of flow there are bubble flow, annular flow, spray flow, and vapor flow. Heat transfer is not very good in the bubble flow and annular flow areas, and the pressure loss for pumping the liquid is large at the annular flow position, making it difficult to match the liquid flow rate to the gas flow rate. There was a problem.

In order to clarify this problem, FIG. 2 shows the flow characteristics of the liquid flowing through the pipe line 1 in the heat exchanger. Conduit 1
Since the heat Q from outside the pipe line 1 is transferred to the liquid 2 flowing through the liquid 2, gas 3 forms bubbles in the liquid 2, resulting in a two-phase flow.

This two-phase flow is a uniform bubble flow at the beginning of the flow (region A).
flows, and the liquid 2 becomes an annular flow that flows in an annular manner near the inner wall surface 4 of the pipe line 1 (area B).

Next, the liquid 2 becomes a spray stream that becomes droplets (zone C)6, and finally it becomes vapor (zone D).

(Problems to be Solved by the Invention) In the area A of the conduit 1 of the conventional heat exchanger, air bubbles are gathered near the inner wall 4 of the conduit 1 to disturb the boundary layer and increase heat transfer efficiency. It is desirable that the flow rate of the liquid 2 is large in the part corresponding to the annular flow in the region B, where the friction between the liquid 2 and the inner wall surface 4 of the pipe line 1 is large and the gas 3 in the center flows in large quantities. There were fewer of them. That is, there was a problem in that it was not possible to achieve a desirable flow of vapor and liquid because heat transfer was undesirable and the pressure loss for pumping the liquid 2 was large.

The present invention improves the flow characteristics in the above-mentioned regions A and B. That is, the purpose of the present invention is to make the liquid flow near the center of the pipe and collect air bubbles near the inner wall of the pipe to improve the heat transfer coefficient, reduce pressure loss, and increase the flow rate of the liquid with a small amount of power. The goal is to provide a way to do so.

(Means for Solving the Problems) In order to achieve the above object, the present invention improves the flow characteristics of two-phase flow as follows.

A wire electrode is provided along the axis of the pipe at the position of the bubble flow and/or annular flow in the pipe through which the two-phase flow is flowing, and a mesh electrode is provided surrounding the outside of the wire electrode, A high voltage is applied between the electrode and the mesh electrode to collect the gas near the inner wall surface of the conduit, creating a liquid flow near the center of the conduit.

Note that the present invention is not limited to improving the flow characteristics of a heat exchanger, but also includes improving the flow characteristics of two-phase flows of liquid and gas in general.

(effect) The invention works like a dog.

When a voltage is applied to a wire electrode and a mesh electrode, the electric field of the wire electrode is stronger than that of the mesh electrode. In gas bubbles with a lower dielectric constant than liquid, the same electrode charge as a wire electrode with a strong electric field is generated at the gas-liquid interface. Therefore, the bubbles are expelled in the direction of the mesh electrode where the electric field is weak.

Further, since the electric field between the mesh electrode and the inner wall of the tube is O, air bubbles are ejected from the hash electrode and exist between the inner wall of the tube and the mesh electrode.

(Example) An example of the present invention will be described below based on FIGS. 1 and 2. This embodiment relates to a heat exchanger in which the flow characteristics of liquid are improved so that a small amount of power is required.

FIG. 1 shows a heat exchanger in which a device 11 for improving flow characteristics is installed at locations corresponding to areas A and B of the above-mentioned pipe line 1.

12 wire electrodes are provided in the pipe 1 along the axial direction of the pipe 1, and a mesh electrode 13 is provided surrounding the outside of the wire electrode 12. The wire electrode 12 and the mesh electrode 13 are in a non-contact state. A high voltage is applied across the line electrode 12 and mesh electrode 13. 14 is a power source.

The electric field of the wire electrode 12 is stronger than the electric field of the mesh electrode 13. The gas-liquid interface has the same charge (
In this embodiment, a positive charge is generated, and the gas 3 is expelled in the direction of the mesh electrode 13 where the electric field is weak. In this way, the gas 3 gathers near the inner wall surface 4 of the pipe 1, and the liquid 2 flows near the center of the pipe 1.

Since the liquid 2 flows near the center of the pipe line 1, pressure loss is small and the flow rate of the liquid 2 can be increased.

In addition, by using this embodiment at a stage when only a small amount of gas 3 is generated, the boundary layer 15 on the inner wall surface 4 of the pipe line 1 is disturbed to help generate more bubbles, thereby reducing the amount of heat transferred to the liquid 2. It is also possible to increase it. That is, when the method according to the present invention is applied to a heat exchanger, it is possible to increase the flow rate of liquid flowing through the pipe line 1 and also to improve the amount of heat transfer.

Other examples include the following. There is a technology that mixes air bubbles into fuel such as gasoline and sends it to a heat engine to prevent the generation of harmful gas. Even in this two-phase flow, the fuel flows along the inner wall surface of the pipe line 1, and there is a risk that an annular flow may occur in which air flows through the center of the pipe line 1. An annular flow is unfavorable for combustion because a large amount of air is sent and only a small amount of fuel is sent.

Therefore, the two-phase flow of fuel and bubbles is carried out using the same device 11 shown in FIG. 1 to collect the bubbles near the inner wall surface 4 of the pipe line 1.
This allows the fuel to flow through the center of the pipe. This allows fuel and air to be delivered in a preferred ratio.

(Effect of the invention) According to the present invention, the following effects are achieved.

Heat transfer can be improved at the location of bubble flow and annular flow in boiling heat exchangers.

Since the liquid flows near the center of the pipe in a two-phase flow in the pipe, there is little pressure loss, and a large amount of liquid can be flowed with a small amount of power.

Furthermore, when transferring a two-phase flow, it is possible to avoid transferring only a large amount of gas.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line I-1 in FIG. Vertical new view showing the flow characteristics of 1: Pipe 2: Liquid 3: Gas 4: Inner wall surface 12: Li electrode 13: Mesh electrode

Claims (1)

[Claims] a wire electrode (12) is provided along the axis of the pipe (1) at the bubble flow (A) and/or annular flow (B) position in the pipe (1) through which the two-phase flow is flowing; A mesh electrode (13) is provided surrounding the outside of the wire electrode (12), and a high voltage is applied between the wire electrode (12) and the mesh electrode (13) to generate the gas (3).
) is collected near the inner wall surface (4) of the pipe (1), and
A method for improving the flow characteristics of a two-phase flow using an electric field, characterized in that a liquid (2) flows near the center of the flow.